Nicola Malafronte

Cultivar based selection and genetic analysis of strawberry fruits with high levels of health promoting compounds

Twenty different strawberry genotypes from phenolic compound content and genetic diversity have been investigated. Twelve phenolic derivatives in the strawberry fruit extracts, their total phenolic content (TPC) and their radical scavenging activity have been quantified. In order to study the influence of the genetic basis of each cultivar (cv) on the chemical composition of fruits, Principal Component Analysis of the obtained data was also used. Significant differences in the content of individual anthocyanins among the 20cvs have been found. Pelargonidin 3-O-glucoside was the predominant anthocyanin in the strawberry extracts with 61.0% of the total anthocyanins in Salva cv, followed by cyanidin 3-O-glucoside. TPC values ranged from 129,96 (Laica cv) to 269,04 (Naiad cv) mg of gallic acid equivalent per 100g of fresh weight and it was congruent previous studies. Moreover RAPD markers have been applied in order to describe their genetic relationships. A total of 32decamer primers were used in RAPD analysis; 19 of them provided at least one polymorphic band, the remaining primers were monomorphic. A total of 124 bands were detected with the mean number of 11.53 accountable fragments per primer and 59.98% were polymorphic. The results of the present study highlighted the health-promoting compound content of strawberry fruits, and provided a good prospect for discriminating strawberries by phenolic content and genetic analysis.

Structural characterization of tetranortriterpenes from Pseudrocedrela kotschyi and Trichilia emetica and study of their activity towards the chaperone Hsp90

Investigation of roots extracts Pseudrocedrela kotschyi and Trichilia emetica led to identification of 5 limonoid derivatives, Kotschyins D-H, and 11 known compounds. Their structures were elucidated by extensive 1D and 2D NMR experiments in conjunction with mass spectrometry. A surface plasmon resonance (SPR) approach was adopted to screen their Hsp90 binding capability and kotschyin D showed a significant affinity for the chaperone. Therefore, the characterization of the biological activity of kotschyin D by means of a panel of chemical and biological approaches, including limited proteolysis, molecular docking and biochemical and cellular assays, was performed. Our result indicated this compound as a type of client selective Hsp90 inhibitor, directly binding to the middle domain of the protein and possibly preventing its interaction with the activator of Hsp90 ATPase 1 (Aha1).

Phenolic Compounds from Olea europaea L. Possess Antioxidant Activity and Inhibit Carbohydrate Metabolizing Enzymes In Vitro

Phenolic composition and biological activities of fruit extracts from Italian and Algerian Olea europaea L. cultivars were studied. Total phenolic and tannin contents were quantified in the extracts. Moreover 14 different phenolic compounds were identified, and their profiles showed remarkable quantitative differences among analysed extracts. Moreover antioxidant and enzymatic inhibition activities were studied. Three complementary assays were used to measure their antioxidant activities and consequently Relative Antioxidant Capacity Index (RACI) was used to compare and easily describe obtained results. Results showed that Chemlal, between Algerian cultivars, and Coratina, among Italian ones, had the highest RACI values. On the other hand all extracts and the most abundant phenolics were tested for their efficiency to inhibit α-amylase and α-glucosidase enzymes. Leccino, among all analysed cultivars, and luteolin, among identified phenolic compounds, were found to be the best inhibitors of α-amylase and α-glucosidase enzymes. Results demonstrated that Olea europaea fruit extracts can represent an important natural source with high antioxidant potential and significant α-amylase and α-glucosidase inhibitory effects.

Antioxidant activities and quali-quantitative analysis of different Smallanthus sonchifolius [(Poepp. and Endl.) H. Robinson] landrace extracts

Five landraces of Smallanthus sonchifolius [(Poepp. and Endl.) H. Robinson], known as yacon, were investigated in total phenolic content, antioxidant activity and chemical composition of ethanol extracts (EEs) and decoction extracts (DEs). The results demonstrated that DEs are rich in phenolic acids as caffeic acid, while the EEs show an higher amount of flavonoids, as luteolin 3′,7-O-diglucoside and luteolin 7-O-glucoside. These flavonoid glycosides were identified for the first time in yacon extracts, together with apigenin and luteolin. The phytochemical profile explains the different antioxidant activities shown in our study. The landraces PER6-DE and PER4-DE showed the highest radical-scavenging activity and reducing power related to their polyphenolic contents. Results also show that yacon can be considered an important source of bioactive compounds with significant differences among the analysed landraces.

Bioactive limonoids from the leaves of Azaridachta indica (Neem).

Eight new limonoids (1-8) and one new phenol glycoside (9), along with six known compounds, were isolated from the leaves of Azaridachta indica. The structures of 1-9 were elucidated on the basis of spectroscopic data analysis. Compounds isolated were assayed for their cytotoxicity against different cancer cell lines. Moreover, their ability to interact with the molecular chaperone Hsp90, affecting its biological activity, was tested.

Identification of Limonol Derivatives as Heat Shock Protein 90 (Hsp90) Inhibitors through a Multidisciplinary Approach.

The identification of inhibitors of Hsp90 is currently a primary goal in the development of more effective drugs for the treatment of various types of multidrug resistant malignancies. In an attempt to identify new small molecules modulating the activity of Hsp90, we screened a small library of tetranortriterpenes. A high-affinity interaction with Hsp90 inducible form was uncovered for eight of these compounds, five of which are described here for the first time. By monitoring the ATPase activity and the citrate synthase thermal induced aggregation, compound 1 (cedrelosin A), 3 (7α-limonylacetate), and 5 (cedrelosin B), containing a limonol moiety, were found to be the most effective in compromising the Hsp90α chaperone activity. Consistent with these findings, the three compounds caused a depletion of c-Raf and pAkt Hsp90 client proteins in HeLa and MCF/7 cell lines. Induced fit docking protocol and molecular dynamics were used to rationalize the structural basis of the biological activity of the limonol derivatives. Taken together, these results point to limonol-derivatives as promising scaffolds for the design of novel Hsp90α inhibitors.

Isolation and structural characterization of glycosides from an anti-angiogenic extract of Monnina obtusifolia H.B.K.

Angiogenesis, the growth of new blood vessels from the pre-existing vasculature is of physiological and pathological importance. Substantial data over the last decade has implicated uncontrolled angiogenesis with various pathological states. Vascular endothelial growth factors (VEGFs) play a critical role in its regulation, and have become one of the most interesting anti-angiogenesis targets. We have investigated the anti-angiogenic potential of plant extracts in a preliminary ELISA screening. The n-BuOH extract obtained from the leaves of Monnina obtusifolia (Polygalaceae) demonstrated an inhibition of VEGF-A or Placental Growth Factor interaction with Flt-1 (VEGF receptor 1), with an inhibition over 50% in particular for VEGF-A/Flt-1 interaction at a concentration of 500 μg/mL. Successively fractionation of the bioactive n-BuOH extracts of M. obtusifolia aerial parts led to the isolation of six new compounds, 1-O-(4-hydroxy-2-methylene-butanoic acid)-6-O-β-D-(4-hydroxy-2-methylene-butanoyl)-glucopyranose (1), 1-O-(isopentenyl)-6-O-β-D-(4-hydroxy-2-methylene-butanoyl)-glucopyranose (2), 1-O-(4-hydroxy-2-methylene-butanoic acid)-6-O-β-D-(isovaleroyl)-glucopyranose (3), 1-O-(3-methylbut-3enyl)-6-O-β-D-(isovaleroyl)-glucopyranose (4), two new sucrose esters, 3,4-O-β-D-di-feruloyl-fructofuranosyl-6-O-α-D-(p-coumaroyl)-glucopyranoside (5), and 3,4-O-β-D-di-feruloyl-fructofuranosyl-6-O-α-D-(caffeoyl)-glucopyranoside (6), together with known flavonoids. Their structures were established on the basis of detailed spectral analysis. Since none of the isolated compounds showed a relevant inhibition of VEGFs, the biological activity observed for the butanolic extract might be due to the presence of a combination of compounds acting synergistically.

Phenolic Derivatives from Ruprechtia polystachya and Their Inhibitory Activities on the Glucose‐6‐phosphatase System

Two new compounds, 5‐methyl‐2‐(2‐methylbutanoyl)phloroglucinol 1‐O‐(6‐O‐β‐D‐apiofuranosyl)‐β‐D‐glucopyranoside (1) and trans‐2,3‐dihydrokaempferol 3‐O‐(4‐O‐sulfo)‐α‐L‐arabinopyranoside (2), together with 14 known flavonoids, trans‐dihydrokaempferol 3‐O‐α‐L‐arabinopyranoside (3), trans‐taxifolin 3‐O‐α‐L‐arabinofuranoside (4), quercetin 3‐O‐α‐L‐rhamnopyranoside (5), quercetin 3′‐O‐α‐L‐arabinofuranoside (6), catechin 3‐O‐α‐L‐rhamnopyranoside (7), trans‐taxifolin 3‐O‐α‐L‐arabinopyranoside (8), cis‐dihydrokaempferol 3‐O‐α‐L‐arabinopyranoside (9), catechin (10), myricetin 3‐O‐α‐L‐rhamnopyranoside (11), quercetin 3‐O‐α‐L‐arabinopyranoside (12), quercetin 3‐O‐α‐L‐arabinofuranoside (13), quercetin 3‐O‐(3″‐galloyl)‐α‐L‐rhamnopyranoside (14), quercetin 3‐O‐(2″‐galloyl)‐α‐L‐rhamnopyranoside (15), and epicatechin 3‐O‐gallate (16), were isolated from the leaves of Ruprechtia polystachya Griseb. (Polygonaceae). Their structures were established on the basis of extensive 1D‐ and 2D‐NMR experiments as well as MS analyses. All compounds, except 1, showed inhibition of the enzyme glucose‐6‐phosphatase in intact microsomes.

Phytochemical and antioxidant activity studies on Ononis angustissima L. aerial parts: isolation of two new flavonoids

Abstract Ononis angustissima aerial parts extract and exudate were subjected to phytochemical and biological studies. Two new natural flavonoids, (3S)-7-hydroxy-4′-methoxy-isoflavanone 3′-β-d-glucopyranoside (1) and kaempferol 3-O-β-d-glucopyranoside-7-O-(2′′′-acetyl)-β-d-galactopyranoside (4), and sixteen known compounds were isolated through a bio-oriented approach. Their structural characterisation was achieved using spectroscopic analyses including 2D NMR. The phytochemical profile of the extracts was also performed, and the antioxidant activity of all compounds was tested by three different assays. To get a trend in the results and to compare the antioxidant capacity among the different methods used, the obtained data were transformed to a relative antioxidant capacity index.

Androstanes and pregnanes from Trichilia emetica ssp. suberosa J.J. de Wilde

Four pregnanes: 1-methoxy-pregnan-17(R)-1,4-dien-3,16-dione (1), 1-methoxy-pregnan-17(S)-1,4-dien-3,16-dione (2), 2,3-seco-pregnan-17(S)-2,3-dioic acid-16-oxo-dimethyl ester (4), 2α,3α,16α-trihydroxy-5α-pregnan-17(R)-20-yl acetate (7), three androstanes: 1-methoxy-androstan-1,4-dien-3,16-dione (3), 2,3-seco-androstan-2,3-dioic acid-16-oxo-dimethyl ester (5), 3-methoxycarbonyl-2,3-seco-androstan-3-oic acid-16-oxo-2,19-lactone (6), together with three known pregnane derivatives, were isolated from the roots of Trichilia emetica ssp. suberosa. Their structures were determined by means of 1D and 2D NMR spectroscopy, mass spectrometry analysis, as well as by quantum chemical calculations.